Picture backed images must have a bit depth and color space

Enforce that picture backed images created by the public API
must have a non-null SkColorSpace.

SkPictureShader uses a private call to get around this restriction.

BUG=skia:

Change-Id: I2fc11a8ffe583035d09e83abf40b827fbf575321
Reviewed-on: https://skia-review.googlesource.com/8415
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>
6 files changed